Portable cookstove



FIG. 1 is a perspective view of a portable cookstove showing my new design;

FIG. 2 is a right side elevational view, the left side being substantially a mirror image thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof; and

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a portable cookstove, as shown and described. 